Incinerator kilns, and especially those of the rotary type, have an outside metallic shell, usually steel, the inside of which is fully covered by a thick ceramic or refractory, usually in the form of fire bricks having a total thickness exceeding in many cases 25 cm. These kilns usually operate at a exit gas or off-gas temperature in the range of about 1,600.degree. to 2,400.degree. F. The ceramic or refractory walls, however, are very vulnerable to erosion and corrosion, due to the hostile conditions created by the nature of incinerated materials and high temperatures, especially, if alkali metals are present.
If the viscosity of slag in the kiln is adequately high, it may form a rather thick viscous coating on the refractory and thus protect it from the hostile environment. However, when the viscosity of the slag is very low, the slag contributes to the erosion and corrosion of the ceramic or refractory, both chemically because it serves as a solvent and mechanically, as it allows foreign big pieces of abrasive material to act against the ceramic walls. If the slag is viscous to the point of becoming substantially solid, or if it has never been formed as a liquid, it becomes ineffective in promoting combustion of organic matter, and also in capturing toxic heavy metals. Therefore, it is imperative that the viscosity of the slag is very carefully monitored and controlled within a range of values. Thus, one of the objects of this invention is to control the viscosity of the slag in incinerating kilns.
U.S. Pat. No. 5,301,621 (Vassiliou et al.), which is incorporated herein by reference, describes methods and devices for slag viscosity detection and control through image analysis of dripping slag within rotary incineration kilns.
U.S. Pat. No. 5,228,398 (Byerly et al.), which is also incorporated herein by reference, describes methods and devices for controlling rotary incineration kilns by determining the position of the kiln outlet at which the slag is exiting.
U.S. Pat. No. 5,353,722 (Vassiliou et al.), which is also incorporated herein by reference, describes preventive slag-viscosity control by detection of alkali metals in the off-gases.
Our co-pending application Ser. No. 08/353,670, filed Dec. 12, 1994, which is also incorporated herein by reference, describes methods and devices for determining the thickness of the protective refractory or ceramic layer by using quantum failure identifiers.
U.S. Pat. No. 5,359,417 (Muller et al.) discloses a method for determination of the field of view observed through a surgical microscope. To achieve this determination, the relative current position of the plane of the field of view to the position of an object detail of interest is detected in a sighting method with the aid of a position detection system operating according to the laser triangulation principle. As soon as the plane of the field of view and the object detail are coincident, then with the aid of detected optical system data, the position of the object detail with reference to the surgical microscope is determined and, with the detected coordinates of the surgical microscope, the position of the field of view is determined in space. The position detecting system required for this purpose operates on an optical basis and can be integrated into the optics of the surgical microscope.
U.S. Pat. No. 5,298,997 (Shintani et al.) discloses a visual inspection method for parts mounted on printed circuit boards. According to this method, three different color light beams which are converged to a single light spot on the surface of a circuit board at predetermined incident angles, are irradiated onto the top surface of an electronic part mounted on the circuit board, then distances between the positions of the top surface of the electronic part to which the light beams are irradiated respectively, from the single light spot on the surface of the circuit board are measured, and the height and an inclined angle of the top surface of the electronic part are computed in accordance with the relationship between the measured distances and the incident angles.
U.S. Pat. No. 5,046,259 (Tusting) discloses measuring systems for making underwater measurements of relative positions and distances between a plurality of objects positioned on an ocean or lake floor basically, which include (a) at least one laser or other light source capable of projecting a collimated light beam therefrom, (b) a pan and tilt unit for moving the source light beam both angularly in vertical planes and in horizontal arcs, (c) a protractor or equivalent for measuring vertical angles through which the longitudinal axis of the light beam is moved by the pan and tilt unit, and (d) a compass unit for determining bearings of vertical plane positions of the light beam relative to magnetic or true north or other azimuth position. The system may include a plurality of lasers and a variety of methods of making measurements with both single and plural laser containing systems are disclosed.
U.S. Pat. No. 4,991,966 (Raymond) discloses an optical positioning method and system, which indicates achievement of a desired distance between a sprayhead and a workpiece. The desired distance is indicated when a primary light pattern converges with a secondary light pattern directed from other than a coaxial orientation. A procedure for programming a workpiece's contours is described, which also allows for visual verification of the program.
U.S. Pat. No. 4,789,243 (Mathur) discloses a system which automatically determines not only a distance from an object surface, but also an orientation of the device with respect to the object surface. This invention also discloses an arrangement of three or more position sensors for determining the orientation of the device, as well as the distance of the device from the object surface. Furthermore, this invention discloses a method of using parameter computation equations for determining the orientation and the distance of the device with respect to the object surface.
U.S. Pat. No. 4,722,605 (Livnat et al.) discloses a Moire system for linear measurement of an unknown distance defined by two surfaces, a collimated light source, a first grating between light source and the surfaces, a second grating positioned to receive collimated light from the surfaces after the light has reached the surfaces from the first grating, the first and second gratings being rotated relative to each other by a small angle .theta., a screen located after the second grating for receiving Moire patterns caused by the first and second grating, and a mechanism for shifting the patterns as a function of the unknown distance whereby measurements of the amount of shifting is determinative of the unknown distance.
U.S. Pat. No. 4,355,904 (Balasubramsnian) discloses a scanning laser measurement system for measuring depthwise variations of surfaces relative to a focal plane of an optical system. Laser light is directed to a test surface, generally aligned with the focal plane, through focusing optics having an optical axis. Some of the light from a beam spot is retro scattered from the test surface and reimaged along a path generally parallel to the optical axis. Depthwise variations in the test surface with respect to the focal plane cause spatial displacements in the retrobeam relative to the optical axis. The retrobeam is directed to a filter which is partially reflective and partially transmissive. A pair of photodetectors is used to intercept reflected and transmitted components of the retrobeam and the intensity of these components is measured and used to compute centroid values for the retrobeam on the filter for various beam spots on the test surface. The computed centroid values are directly proportional to depthwise surface deviations from the focal plane. The beam is directed to various points on the test surface by an optical scanner. If the deviations in the test surface from the focal plane are so great that a retrobeam cannot be formed, the entire optical system is translated until beam focus can be achieved and a retrobeam formed. The extent of translation is a coarse measurement of depthwise variations in the test surface relative to the focal plane, while the previously mentioned centroid values yield a fine measurement of depthwise variations relative to the focal plane.
U.S. Pat. No. 3,817,619 (Kawahara) discloses a device for measuring the distance of an object from the forward end portion of an endoscope adapted to be inserted into a hollow portion of a living body or the like for the inspection thereof. The forward end portion of the endoscope is connected to a control housing through an elongated tube. The image of an object being viewed is formed in the forward end portion of an objective lens system, and the image is transmitted through the elongated tube by an ocular means provided in the control housing. The distance between the object and the forward end portion of the endoscope is determined using two beams of light emitted from the forward end portion toward the object so as to form a pair of light spots thereon. The distance of the object from the forward end portion of the endoscope may be determined by measuring the relative positions of the light spots with respect to the field of view of the endoscope. The distance of the object may also be determined by measuring the amount of change in direction of either or both of the beams of light required to bring the two light spots appearing in the field of view into registration.
U.S. Pat. No. 3,614,228 (Lyon) discloses an optical range finder having nonoverlapping complete images. According to this method, a 90-100 percent reflective first surface mirror is disposed to direct a reflected image to a 70 percent reflective, 30 percent transmitting beam splitter which reflects the reflected image along a light path parallel to the light path of the true image to thereby produce two separate full view images. The true image and reflected image are directed through a magnifying telescope having infinite projected crossed vertical and horizontal reticles. The mirror is rotatable to change the vertical displacement of the reflected image from the horizontal reticle and when the two images are equally displaced from the horizontal reticle, the range of the image may be found by triangulation.
U.S. Pat. No. 3,340,393 (Landes et al.) discloses a machine with lining bricks which have a face exposed to wear and side and end surfaces which equal the thickness of the bricks and are concealed by adjacent bricks, said thickness defining surfaces having applied thereto wear indicating means. Said means comprise a right angle triangular design in which one of the right angle edges is perpendicular to the exposed face of the brick and located at a distance from the adjacent parallel edge of the thickness defining surface to which the design is applied, the other of its right angle side edges being coincident with and visible at the exposed face of the brick, both said side edges being equal in length to the thickness of the brick. The length of the visible edge of the triangular design changes progressively as the exposed face becomes worn and at all times equals the thickness of the brick.
U.S. Pat. No. 2,289,877 (Davis) discloses refractory lining for rotary kilns, and refractory members useful for forming such lining, as well as processes for making the same.
None of the above references discloses, suggests, or implies methods or devices for determining and controlling the thickness of a protective layer in a kiln as described and claimed in the instant invention.